Thanks for that both of you. Martin would you say you find if fires off late? Is that something that can be rectified?
Many thanks:

Hi all i have just joined.
I have a Pentax K5 and a K100D, i am doing a course at the moment and hoping to have a part time business up and running by the end of the year.
I am reading Strobist at the moment and don't have an off camera flash that is portable. So i am looking for any recommendations for a cheap but effective flash i can use portably.
I don't want to spend too much as i just bought studio lighting (Gemini kit)but it's not that easy to carry around or use on an outdoor shoot.
I have seen others talking about the AF540 but it is expensive. Is it worth saving to buy that or getting something a bit cheaper?
Thanks for reading
Jayne